Fuel ignition control



May 19, 1953 M. F. PETERS 2,639,408

FUEL: IGNITION CONTROL Filed Nov. l2, 1949 Patented May 19, 1953 UNITED STATES ram yoFiicE FUEL IGNITION CONTROL Melville F. Peters, East Orange, N. J.

Application November 12, 1949,v Serial No. 126,771

' This invention relates to fuel ignition, and

particularly to the ignition of vaporized fuel in a combustion chamber, as for example, the cylinder, or cylinders, of an internal combustion engine.

In conventional high-tension ignition systems lfor multi-cylinder engines, an ignition current ow begins when the spark generator of the primary circuit develops a voltage of suicient magnitude to induce in the secondary circuit a peak voltage of a value (hereinafter referred to as -V1) high enough to bridge the distributor gap.

When this occurs, there is a flow of high-tension current in the ignition circuit; and this energy flow continues to increase until the voltage across f .the spark plug electrodes reaches a suilicient lof flow occurs, however, there is still a substantial potential diiierence remaining between'end points of the conductors, as for example, between the distributor end of the ignition cable, on the one hand, and the central (insulated) electrode of the spark plug, on the other. The magnitude of this remaining potential diierence is substantial, whether the engine has been in e constant operation for a period of time, or whether it is being started from a co-ld condition; but it is relatively much greater during the starting eiort, as will be seen from the fol- 4lowing analysis of the two extreme conditions:

L Ncrmal operation During normal operation, with the usual relatively small gap at the distributor, the breakdown voltage V1 of the distributor gap may be of the order of 1500 to 2000 volts, and the spark discharge voltage V2 will be correspondingly low; similarly, the healing voltage V3 will be still lower because, during such normal operation, the spark discharge is occurring across a space enveloped by hot ionized gases, hence, the residu-al voltage on the secondary circuit, while not zero, is not great enough to interfere with normal functioning of the operating cycle.

II.-Sta1ting By starting" is meant the period of time before sustained combustion occurs in the engine cylinders. At this time, the spark plug electrodes are cold, and the voltage V2 to be de- 2 Claims. (Cl. 315-59) veloped before the electrodes will function is correspondingly high. For the same reasons the voltage V3 at which healing of the gap will occur is also high. Hence, there will be an appreciable potential difference remaining on the ignition cable, particularly as the first spark discharge occurs without benefit of any noteworthy assistance from the surrounding gases in the cylinder, as the latter do not become hot, or ionized, until a later stage of operation. This inherent potential difference, from the cable to ground, is greatly augmented when accompanied by a condition of worn electrodes at the distributor and plug gaps. Moreover, ifthe charge remaining on the cable is of the same polarity, as

`it may well be, it may render the spark generator ineffective, as the maximum voltage capacity of the latter may be less than that required to bridge a worn distributor gap, against the residual voltage remaining on the cable, at the termination of the rst abortive spark discharging cycle.

The present invention solves the diiculties just described by introducing a new step in the ignition control cycle, namely, the step of connecting the ignition cable to ground, over a path of calculated resistance value, which path, will remain permanently effective as a cable potential venting instrumentality, not only during normal engine operation but also in the intervals between successive uses of the engine. By introducing this step of constantly venting the cable to the ground, I provide a positive insurance against reversely loading the spark generator to a point where spark production becomes uncertain. At the same time, the resistance of the venting path can be kept high enough to prevent its seriously affecting the peak voltage capacity of the spark generator.

Accordingly, objects of the invention are:

1. To provide a novel method of controlling the behavior of a. fuel ignition circuit, which novel method involves the continuous Venting of each ignition cable to ground, over a venting path whose resistance is of a pre-established value that is sufficiently-low to insure against maintenance of any substantial residual potential difference to ground in the cable during the engine starting period, yet suiciently high to prevent any appreciable dro-p in the peak voltage at which spark discharge occurs.

2. To provide, in an ignition system, in combination with each ignition cable, a relatively high resistance element having one of its terminals connected to ground and the other of its terminals continuously connected in circuit with said cable.

3. To provide, in an ignition system, in combination with each spark plug, a resistance element constituting shunt path by which the locked-in portion of the energy developed in the system will escape to ground, and thus, clear the spark plug circuits of all residual charges that might, if allowed to remain in storage in said circuits, interfere With proper functioning of the spark discharge electrodes of the plugs; and

4. To provide a spark plug of novel construction, including such a grounding resistor as .an integral part of the plug. n

These and other objects of the invention will be better understood upon reference to the accompanying drawing, wherein, Figure No. 1 is a sectional View of a spark plug embodying the invention; and, Figure Nol 2 is a diagram of electrical connections toisuch a plug. y

Referring first to. Figure' No. 2, there is illustrated, schematically, an ignition system including a spark generator G, a distributor d, a pair of spark plug electrodes PrP-P2, a cable'N" connecting one of the contacts of distributor d with the first electrode P1 of the spark plug, a ground connection Gr, leading from the second spark plug electrode P2, and a resistor R, having one terminal connected directlyto the electrode P1, and its other terminal grounded at G12; Figure No. l shows this resistor B, (merely by wayv of indicating oneoi many suitable physical locationsv and arrangements), as disposed laterally of the central electrode Pi, in a hole drilled into the ceramic body 6 of thelplug; theA resistor having its inner capped end pressed .against the electrode P, by the pressure of the shell 1 against the outer capped end or" the resistor. Being in capsule form, the resistor is readily insertible into the Vbody 6, prior to assembly of the body and shell; the body being retained in the Shell by turning over the shcil end 8,as usualin the art.

In operation, resistorRwill serve as av constant venting means between the cable N and the grounded shell 7, so that no residual potential difference will remain on the cable, to interfere with spark production, especially when the engine is cold. The value chosen for resistor R (the same will apply as to the resistors R, for the other spark plugs not shown) Will be low enough to produce the desired cable venting, yet, high enough so that it will not appreciably aiiect the gap break-down voltage characteristics of the particular circuit employed in any given installation, as heretofore explained.

The invention, of course, embraces physical relationships deviating from those illustrated and, in fact, all embodiments based upon the teaching disclosed herein.

What I claim is:

l. In an ignition system, in combination With each individual ignition current supply circuit, a circuit venting path operable as an integral part of each successive cycle of operation of the system, during normal use of the system, at its normal operating voltage, said path including a relatively high resistance element having one of its terminals connected to ground and the other of its terminals continuously and permanentiy connected in series with said current supply circuit.

2. In a spark plug having an insuiated electrode terminating in a point. of spark discharge, the combination with said electrode of a permanently operating venting path including a relatively high resistance element permanently incorporated within the plug, and having one of its terminals connected to ground and the other of its terminals connected directly to said electrode.

MELVILLE F. PETERS.

Number v 2,323,913 l 

